Definition
Treasury bills are sold at public auctions every week. The 6-month bill is also known as the 26- week bill. Competitive bids at these auctions determine the interest rate paid on each issue. A group of securities dealers, known as primary dealers, are authorized and obligated to submit competitive tenders at Treasury auctions. Dealers can hold the bills, resell the bills to their clients or trade them with other securities firms. Typically, the New York Fed approves about 20 securities firms to be primary dealers but that number dropped sharply during the recent financial crisis as some were merged into other firms or went bankrupt. The Fed has been rebuilding that number regularly and the latest list can be found here. Since these are public auctions, the Treasury must announce the size, date and time of the auction every week. Six-month bills are announced on Thursday for auction the following Monday and issued (settled) on Thursday. If a Monday is a banking holiday, the bills are auctioned on Tuesday. (Department of the Treasury)
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